Globalsat ET-318 User Manual

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環天衛星科技股份有限公司

PRODUCT USER MANUAL

GPS ENGINE BOARD

ET-318

Version 1.0

GlobalSat Technology Corporation 台北縣中和市建一路 186 號 16 樓(遠東世紀廣場)

16, No.186,Chien 1 Road, 235Chung Ho City,Taipei Hsien, Taiwan ,R.O.C.

Tel: 886-2-8226-3799(Rep.) Fax: 886-2-8226-3899 Web: www.globalsat.com.tw E-mail: service@globalsat.com.tw

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Features:

SiRF starⅢ high performance GPS Chip Set Very high sensitivity (Tracking Sensitivity: -159 dBm) Extremely fast TTFF (Time To First Fix) at low signal level Compact size (15.2mm * 14 mm * 2.8mm) suitable for space-sensitive application One size component, easy to mount on another PCB board Support NMEA 0183 and SiRF binary protocol

Specification:

General

Chipset SiRF StarⅢ Frequency L1, 1575.42 MHz C/A code 1.023 MHz chip rate Channels 20 channel all-in-view tracking Sensitivity -159 dBm

Accuracy

Position 10 meters, 2D RMS 5 meters, 2D RMS, WAAS enabled Velocity 0.1 m/s Time 1us synchronized to GPS time

Datum

Default WGS-84

Acquisition Time

Reacquisition 0.1 sec., average Hot start 1 sec., average Warm start 38 sec., average Cold start 42 sec., average

Dynamic Conditions

Altitude 18,000 meters (60,000 feet) max Velocity 515 meters /second (1000 knots) max Acceleration Less than 4g Jerk 20m/sec **3

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Power

Main power input 3.3V +- 5% DC input Power consumption 42mA (Continuous mode) 36mA (Trickle power mode

Interface

Dimension 15.2mm * 14 mm * 2.8mm Baud rate 4,800 to 57,600 bps adjustable Output message SiRF binary or

NMEA 0183 GGA, GSA, GSV, RMC, VTG, GLL

GPS Passive (or Active )Antenna Specification(Recommendation)

Frequency: 1575.42+2 MHz

Axial Ratio: 3 dB Typical

output Impedance: 50Ω

Polarization: RHCP

Output VSWR: 1.5 Max.

Active option

Low Noise Amplifter:

Amplifier Gain :20~26dB Typical

Output VSWR: 2.0 Max.

Noise Figure: 2.0 dB Max.

Environmental

Operating Temperature -40℃ to +85℃ Storage Temperature: -40℃ to +85℃

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Pin Assignment

Pin Signal Name I/O Description

1 GND G Analog Ground 2 RF_IN RF GPS Signal input 3 GND G Analog Ground 4 NRESET I Reset (Active low) 5 VCC_IN PWR DC Supply Voltage input 6 VBAT PWR Backup voltage supply 7 RXB I Serial port B 8 TXB O Serial port B 9 GND G Analog Ground

10 BOOTSEL Boot mode

11 TXA O Serial port A 12 RXA I Serial port A 13 GPIO1 I General –purpose I/O 14 GPIO14 I General –purpose I/O 15 TIMEMARK O One pulse per second 16 GPIO13 I General –purpose I/O

17 GPIO15 I General –purpose I/O

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Definition of Pin assignment

VCC_IN

This is the main DC supply for a 3.3V +- 5% DC input power module board.

GND

GND provides the ground for digital pa

BOOTSEL

rt.

Set this pin to high for programming flash.

RXA

This is the main receiver channel and is used to receive software commands to

the

board from SIRFdemo software or from user written software.

PS:

RXB

Pull up

not used.

This is the auxiliary receiving channel and is used to input differential

corrections

Pull up

PS:

TXA

This is the main transmitting channel and is used to output

navigation and measurement data to SiRFdemo or user written software.

TXB

the board to enable DGPS navigation.

not used.

For user’s application (not currently used).

RF_IN

This pin receiver signal of GPS analog .due to the RF characteristics of the

signal

the design has to certain criteria. The line on the PCB from the

antenna(or

PPS

This pin provides one pulse-per-second output from the board,

which is synchronized to GPS time. This is not available in Trickle Power

antenna connector) has to be a controlled microstrip line at 50Ω

mode

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Backup battery (V_BAT)

This is the battery backup input that powers the SRAM and RTC when main power is removed. Typical current draw is 15uA. Without an external backup battery, the module/engine board will execute a cold star after every turn on. To achieve the faster start-up offered by a hot or warm start, a battery backup must be connected. The battery voltage should be between 2.0v and 5.0v.

TIMEMARK

This pin provides one pulse-per-second output from the

board, which is synchronized to GPS time. This is not available in Trickle

Power mode

GPIO

Functions

Several I/Os are connected to the digital interface connector

for custom applications

Application Circuit

Antenna

LNA

3.3V

BATTERY

1 2

0.1U

1 2

R46

1 2

560R

VCC_RF

1 2

SAW FI LTER

option

RB715F

50 ohm m icros trip line

RESET

RXB

TXB

GND

RF_IN

GND

NRESET

VCC_I N

VBAT

RXB

TXB

GPS

GPIO15

GPIO13

TI MEMARK

GPIO14

GPIO1

RXA

TXA

BOOTSEL

GND

GPIO15

GPIO13

TI MEMARK

GPIO14

GPIO1

RXA

TXA

BOOTSEL

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Recommend Layout PAD

Mechanical Layout

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N N

SOFTWARE COMMAND

NMEA Output Command

GGA-Global Positioning System Fixed Data

Table B-2 contains the values for the following example:

$GPGGA,161229.487,3723.2475,N,12158.3416,W,1,07,1.0,9.0,M,,,,0000*18

Table B-2 GGA Data Format

Name Example Units Description

Message ID $GPGGA GGA protocol heade UTC Time 161229.487 hhmmss.sss Latitude 3723.2475 ddmm.mmmm

/S Indicator Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes Position Fix Indicator 1 See Table B-3 Satellites Used 07 Range 0 to 12 HDOP 1.0 Horizontal Dilution of Precision MSL Altitude1 9.0 meters Units M meters Geoid Separation

meters Units M meters Age of Diff. Corr. second Diff. Ref. Station ID 0000 Checksum *18 <CR><LF> End of message termination

SiRF Technology Inc. does not support geoid corrections. Values are WGS84 ellipsoid heights.

=north or S=south

ull fields when DGPS is not used

Table B-3 Position Fix Indicator

Valu e Descri 0 Fix not available or invali 1 GPS SPS Mode, fix vali 2 Differential GPS, SPS Mode , fix vali 3 GPS PPS Mode, fix vali

tion

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GLL-Geographic Position-Latitude/Longitude

Table B-4 contains the values for the following example:

$GPGLL,3723.2475,N,12158.3416,W,161229.487,A*2C

Table B-4 GLL Data Format Name Exam

Message ID $GPGLL GLL protocol heade Latitude 3723.2475 ddmm.mmmm

/S Indicator n Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes UTC Position 161229.487 hhmmss.sss Status A A=data valid or V=data not valid Checksum *2C <CR><LF> End of message termination

le Units Description

=north or S=south

GSA-GNSS DOP and Active Satellites Table B-5 contains the values for the following example:

$GPGSA,A,3,07,02,26,27,09,04,15,,,,,,1.8,1.0,1.5*33

Table B-5 GSA Data Format

Name Example Units Description

Message ID $GPGSA GSA pr ot ocol header Mode1 A See Table B-6 Mode2 3 See Table B-7 Satellite Used1 07 Sv on Channel 1 Satellite Used1 02 Sv on Channel 2 ….. Satellite Used1 Sv on Channel 12 PDOP 1.8 Position dilution of Precision HDOP 1.0 Horizontal dilution of Precision VDOP 1.5 Vertical dilution of Precision Checksum *33 <CR><LF> End of message termination

1. Satellite used in solution.

Table B-6 Mode1

Value Description

M Manual-forced to operate in 2D or 3D mode A 2Dautomatic-allowed to automatically switch 2D/3D

Table B-7 Mode 2

Value Description

1 Fix Not Available 2 2D 3 3D

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GSV-GNSS Satellites in View

)

N N

Table B-8 contains the values for the following example:

$GPGSV,2,1,07,07,79,048,42,02,51,062,43,26,36,256,42,27,27,138,42*71 $GPGSV,2,2,07,09,23,313,42,04,19,159,41,15,12,041,42*41 Table B-8 GSV Data Format

Name Example Descriptio

Message ID $GPGSV GSV protocol heade

umber of Messages1 2 Range 1 to 3 Message Numbe Satellites in View 07 Satellite ID 07 Channel 1(Range 1 to 32 Elevation 79 degrees Channel 1(Maximum90 Azimuth 048 degrees Channel 1(True, Range 0 to 359) SNR(C/No) 42 dBHz Range 0 to 99,null when not tracking ……. ……. Satellite ID 27 Channel 4 (Range 1 to 32 Elevation 27 Degrees Channel 4(Maximum90 Azimuth 138 Degrees Channel 4(True, Range 0 to 359) SNR(C/No) 42 dBHz Range 0 to 99,null when not tracking Checksum *71 <CR><LF> End of message termination

Depending on the number of satellites tracked multiple messages of GSV data may be required.

1 Range 1 to 3

RMC-Recommended Minimum Specific GNSS Data

Table B-10 contains the values for the following example:

$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598,,*10 Table B-10 RMC Data Format

Name Example Units Description

Message ID $GPRMC RMC protocol header UTC Time 161229.487 hhmmss.sss Status A A=data valid or V=data not valid Latitude 3723.2475 ddmm.mmmm

/S Indicator Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes Speed Over Ground 0.13 knots Course Over Ground 309.62 degrees True Date 120598 ddmm Magnetic Variation2 degrees E=east or W=wes Checksum *10 <CR><LF> End of message termination SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are

=north or S=south

geodetic WGS48 directions.

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VTG-Course Over Ground and Ground Speed

$GPVTG,309.62,T,,M,0.13,N,0.2,K*6E

Name Example Units Description

Message ID $GPVTG VTG protocol header Course 309.62 degrees Measured headin Reference T True Course degrees Measured headin Reference M Magnetic Speed 0.13 knots Measured horizontal speed Units Speed 0.2 Km/h Units K Kilometers per hour Checksum *6E <CR><LF> End of message termination

Knots

Measured horizontal speed

2.2 NMEA Input Command

A). Set Serial Port ID:100 Set PORTA parameters and protocol

This command message is used to set the protocol(SiRF Binary, NMEA, or USER1) and/or the communication parameters(baud, data bits, stop bits, parity). Generally,this command would be used to switch the module back to SiRF Binary protocol mode where a more extensive command message set is available. For example,to change navigation parameters. When a valid message is received,the parameters will be stored in battery backed SRAM and then the receiver will restart using the saved parameters.

Format:

$PSRF100,<protocol>,<baud>,<DataBits>,<StopBits>,<Parity>*CKSUM <CR><LF>

<protocol> 0=SiRF Binary, 1=NMEA, 4=USER1 <baud> 1200, 2400, 4800, 9600, 19200, 38400 <DataBits> 8,7. Note that SiRF protocol is only valid f8

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Data bits <StopBits> 0,1 <Parity> 0=None, 1=Odd, 2=Even

Example 1: Switch to SiRF Binary protocol at 9600,8,N,1

$PSRF100,0,9600,8,1,0*0C<CR><LF>

Example 2: Switch to User1 protocol at 38400,8,N,1

$PSRF100,4,38400,8,1,0*38<CR><LF>

**Checksum Field: The absolute value calculated by exclusive-OR the

8 data bits of each character in the Sentence,between, but excluding “$” and “*”. The hexadecimal value of the most significant and least significant 4 bits of the result are convertted to two ASCII characters (0-9,A-F) for transmission. The most

significant character is transmitted first.

**<CR><LF> : Hex 0D 0A

B). Navigation lnitialization ID：101 Parameters required for start

This command is used to initialize the module for a warm start, by providing current position （in X, Y, Z coordinates）,clock offset, and time. This enables the receiver

to search for the correct satellite signals at the correct signal parameters. Correct initialization parameters will enable the receiver to acquire signals m o re quickly, and thus, produce a faster navigational solution.

When a valid Navigation Initialization command is received, the receiver will restart using the input parameters as a basis for satellite selection and acquisition.

Format：

$PSRF101,<X>,<Y>,<Z>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,<chnlCount>,<R esetCfg> *CKSUM<CR><LF>

<X> X coordinate position

INT32

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<Y> Y coordinate position

INT32

<Z> Z coordinate position

INT32

<ClkOffset> Clock offset of the receiver in Hz, Use 0 for

last saved value if available. If this is unavailable, a default value of 75000 for GSP1, 95000 for GSP 1/LX will be used.

INT32

<TimeOf Week> GPS Time Of Week

UINT32

<WeekNo> GPS Week Number

UINT16 （ Week No and Time Of Week calculation

from UTC time）

<chnlCount> Number of channels to use.1-12. If your

CPU throughput is not high enough, you could decrease needed throughput by reducing the number of active channels

UBYTE

<ResetCfg> bit mask

0×01=Data Valid warm/hotstarts=1 0×02=clear ephemeris warm start=1 0×04=clear memory. Cold start=1 UBYTE

Example: Start using known position and time. ＄PSRF101,-2686700,-4304200,3851624,96000,497260,921,12,3*7F

C). Set DGPS Port ID:102 Set PORT B parameters for DGPS input

This command is used to control Serial Port B that is an input only serial port used to receive RTCM differential corrections. Differential receivers may output corrections using different communication parameters.

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The default communication parameters for PORT B are 9600 Baud, 8data bits, 0 stop bits, and no parity. If a DGPS receiver is used which has different communication parameters, use this command to allow the receiver to correctly decode the data. When a valid message is received, the parameters will be stored in battery backed SRAM and then the receiver will restart using the saved parameters. Format: ＄PSRF102,<Baud>,<DataBits>,<StopBits>,<Parity>*CKSUM<CR><LF>

<baud> 1200,2400,4800,9600,19200,38400 <DataBits> 8 <StopBits> 0,1 <Parity> 0=None,Odd=1,Even=2

Example: Set DGPS Port to be 9600,8,N,1

＄PSRF102,9600,8,1.0*12

D). Query/Rate Control ID:103 Query standard NMEA message and/or set output rate

This command is used to control the output of standard NMEA message GGA,

GLL, GSA, GSV

RMC, VTG. Using this command message, standard NMEA message may be

polled once, or setup for periodic output. Checksums may also be enabled or disabled depending on the needs of the receiving program. NMEA message settings are saved in battery backed memory for each entry when the message is accepted.

Format: ＄PSRF103,<msg>,<mode>,<rate>,<cksumEnable>*CKSUM<CR><LF>

<msg> 0=GGA,1=GLL,2=GSA,3=GSV,4=RMC,5=VTG <mode> 0=SetRate,1=Query <rate> Output every <rate>seconds, off=0,max=255 <cksumEnable> 0=disable Checksum,1=Enable checksum

for specified message

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Example 1: Query the GGA message with checksum enabled

＄PSRF103,00,01,00,01*25

Example 2: Enable VTG message for a 1Hz constant output with checksum

enabled

＄PSRF103,05,00,01,01*20

Example 3: Disable VTG message

＄PSRF103,05,00,00,01*21

E). LLA Navigation lnitialization ID:104 Parameters required to start using Lat/Lon/Alt

This command is used to initialize the module for a warm start, by providing current position (in Latitude, Longitude, Altitude coordinates), clock offset, and time. This enables the receiver to search for the correct satellite signals at the correct signal parameters. Correct initialization parameters will enable the receiver to acquire signals more quickly, and thus, will produce a faster navigational soution. When a valid LLANavigationInitialization command is received,the receiver will restart using the input parameters as a basis for satellite selection and acquisition.

Format:

＄PSRF104,<Lat>,<Lon>,<Alt>,<ClkOffset>,<TimeOfWeek>,<WeekNo>, <ChannelCount>, <ResetCfg>*CKSUM<CR><LF>

<Lat> Latitude position, assumed positive north of equator and

negative south of equator float, possibly signed

<Lon> Longitude position, it is assumed positive east of Greenwich

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and negative west of Greenwich

Float, possibly signed

<Alt> Altitude position

float, possibly signed

<ClkOffset> Clock Offset of the receiver in Hz, use 0 for last saved value if

available. If this is unavailable, a default value of 75000 for

GSP1, 95000 for GSP1/LX will be used. INT32 <TimeOfWeek> GPS Time Of Week UINT32 <WeekNo> GPS Week Number UINT16 <ChannelCount> Number of channels to use. 1-12

UBYTE

<ResetCfg> bit mask 0×01=Data Valid warm/hot starts=1 0×02=clear ephemeris warm start=1 0×04=clear memory. Cold start=1

UBYTE Example: Start using known position and tim e. ＄PSRF104,37.3875111,-121.97232,0,96000,237759,922,12,3*37

F). Development Data On/Off ID:105 Switch Development Data Messages On/Off

Use this command to enable development debug information if you are having trouble getting commands accepted. Invalid commands will generate debug information that should enable the user to determine the source of the command rejection. Common reasons for input command rejection are invalid checksum or parameter out of specified range. This setting is not preserved across a module reset.

Format: ＄PSRF105,<debug>*CKSUM<CR><LF>

<debug> 0=Off,1=On

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Example: Debug On ＄PSRF105,1*3E Example: Debug Off ＄PSRF105,0*3F

G). Select Datum ID:106 Selection of datum to be used for coordinate Transformations

GPS receivers perform initial position and velocity calculations using an earth-centered earth-fixed (ECEF) coordinate system. Results may be converted to an earth model (geoid) defined by the selected datum. The default datum is WGS 84 (World Geodetic System 1984) which provides a worldwide common grid system that may be translated into local coordinate systems or map datums. (Local map datums are a best fit to the local shape of the earth and not valid worldwide.)

Examples: Datum select TOKYO_MEAN $PSRF106,178*32